<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>浮动布局</title>
  <style>
    * {
      box-sizing: border-box;
    }

    .container {
      width: 100%;
      overflow: auto;
    }

    .left {
      float: left;
      width: 30%;
      background-color: #f0f0f0;
      padding: 20px;
    }

    .right {
      float: left;
      width: 70%;
      background-color: #e0e0e0;
      padding: 20px;
    }
  </style>
</head>

<body>
  <div class="container">
    <div class="left">
      <p>左侧内容</p>
    </div>
    <div class="right">
      <p>右侧内容</p>
    </div>
  </div>
</body>

</html>